Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique holding significant promise as a tool for cognitive neuroscience, and for psychiatric treatment of neurological disorders. In TMS, one or more coils carrying time varying current located near the scalp generate magnetic fields inside the head that in turn induce electric fields and eddy-currents inside conductive brain tissue. Whenever a nerve fiber is aligned with the induced electric field, a current is produced in the axon, which in turn depolarizes its membrane. A large induced electric field is essential for neuronal stimulation. TMS coils generate substantial unwanted stimulation outside the desired region, and stimulate large regions of tissue limited to areas near the surface of the brain because the electric field becomes diffuse and decays rapidly with increasing distance from the coil.
Historically, numerous attempts have been made to design TMS coils capable of delivering more focused electric fields deep into the brain. For example, many single coil topologies have been explored. Further improvements are needed. Accordingly, this disclosure introduces a multi-channel coil array design that stimulates a specific target region while minimizing stimulation elsewhere.
This section provides background information related to the present disclosure which is not necessarily prior art.